Package org.geotools.data.transform

Class TransformFeatureSource

Object

TransformFeatureSource

All Implemented Interfaces:

FeatureSource<SimpleFeatureType,SimpleFeature>, SimpleFeatureSource

Direct Known Subclasses:

TransformFeatureStore

public class TransformFeatureSource
extends Object
implements SimpleFeatureSource

A feature source that can transform a source feature source using a set of expressions

Usages:

• hide, rename fields - compute new fields
• build geom from x,y (we need to add a new Point filter function and have a special treatment of it in simplifying filter visitor so that it turns bbox filters against it into a filter on x,y)
• on the fly simplification for WFS (just use environment variables) and in general dynamic processing based on params without stored queries

Author:

Andrea Aime - GeoSolutions

Field Summary

Fields

Modifier and Type	Field	Description
protected static final FilterFactory	FF
protected static final Logger	LOGGER
protected SimpleFeatureSource	source
protected Transformer	transformer

Constructor Summary

Constructors

Constructor	Description
TransformFeatureSource(SimpleFeatureSource source, Name name, List<Definition> definitions)	Creates a transformed feature source from the original source, giving it a certain name and a set of computed properties

Method Summary

Modifier and Type	Method	Description
void	addFeatureListener(FeatureListener listener)	Registers a listening object that will be notified of changes to this FeatureSource.
ReferencedEnvelope	getBounds()	Get the spatial bounds of the feature data.
ReferencedEnvelope	getBounds(Query query)	Get the spatial bounds of the features that would be returned by the given Query.
int	getCount(Query query)	Gets the number of the features that would be returned by the given Query, taking into account any settings for max features and start index set on the Query.
DataAccess<SimpleFeatureType,SimpleFeature>	getDataStore()	Returns the data source, as a DataAccess object, providing this FeatureSource.
SimpleFeatureCollection	getFeatures()	Retrieves all features in the form of a FeatureCollection.
SimpleFeatureCollection	getFeatures(Query query)	Retrieves features, in the form of a FeatureCollection, based on a Query.
SimpleFeatureCollection	getFeatures(Filter filter)	Retrieves features, in the form of a FeatureCollection, based on an OGC Filter.
ResourceInfo	getInfo()	Returns information describing this FeatureSource which may include title, description and spatial parameters.
Name	getName()	Returns the name of the features (strictly, the name of the AttributeDescriptor for the features) accessible through this FeatureSource.
QueryCapabilities	getQueryCapabilities()	Enquire what what query capabilities this FeatureSource natively supports.
SimpleFeatureType	getSchema()	Retrieves the schema (feature type) that will apply to features retrieved from this FeatureSource.
Set<RenderingHints.Key>	getSupportedHints()	Returns the set of hints that this FeatureSource supports via Query requests.
void	removeFeatureListener(FeatureListener listener)	Removes an object from this FeatureSource's listeners.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

LOGGER

protected static final Logger LOGGER

FF

protected static final FilterFactory FF

transformer

protected Transformer transformer

source

protected SimpleFeatureSource source

Constructor Details

TransformFeatureSource

public TransformFeatureSource(SimpleFeatureSource source,
 Name name,
 List<Definition> definitions)
                       throws IOException

Creates a transformed feature source from the original source, giving it a certain name and a set of computed properties

Throws:

IOException

Method Details

getName

public Name getName()

Description copied from interface: FeatureSource

Returns the name of the features (strictly, the name of the AttributeDescriptor for the features) accessible through this FeatureSource.

The value returned by this method can be different to that returned by featureSource.getSchema().getType().getName(). This is because there is a distinction between the name applied to features and the name of a feature type. When working with SimpleFeature and SimpleFeatureType, for example with a shapefile data source, it is common practice for feature and feature type names to be the same. However, this is not the case more generally. For instance, a database can contain two tables with the same structure. The feature name will refer to the table while the feature type name refers to the schema (table structure).

Specified by:

getName in interface FeatureSource<SimpleFeatureType,SimpleFeature>

Returns:

the name of the features accessible through this FeatureSource

getInfo

public ResourceInfo getInfo()

Description copied from interface: FeatureSource

Returns information describing this FeatureSource which may include title, description and spatial parameters. Note that in the returned ResourceInfo object, the distinction between feature name and schema (feature type) name applies as discussed for FeatureSource.getName().

Specified by:

getInfo in interface FeatureSource<SimpleFeatureType,SimpleFeature>

getDataStore

public DataAccess<SimpleFeatureType,SimpleFeature> getDataStore()

Description copied from interface: FeatureSource

Returns the data source, as a DataAccess object, providing this FeatureSource.

Specified by:

getDataStore in interface FeatureSource<SimpleFeatureType,SimpleFeature>

Returns:

the data source providing this FeatureSource

getQueryCapabilities

public QueryCapabilities getQueryCapabilities()

Description copied from interface: FeatureSource

Enquire what what query capabilities this FeatureSource natively supports. For example, whether queries can return sorted results.

Specified by:

getQueryCapabilities in interface FeatureSource<SimpleFeatureType,SimpleFeature>

Returns:

the native query capabilities of this FeatureSource

addFeatureListener

public void addFeatureListener(FeatureListener listener)

Description copied from interface: FeatureSource

Registers a listening object that will be notified of changes to this FeatureSource.

Specified by:

addFeatureListener in interface FeatureSource<SimpleFeatureType,SimpleFeature>

Parameters:

listener - the new listener

removeFeatureListener

public void removeFeatureListener(FeatureListener listener)

Description copied from interface: FeatureSource

Removes an object from this FeatureSource's listeners.

Specified by:

removeFeatureListener in interface FeatureSource<SimpleFeatureType,SimpleFeature>

Parameters:

listener - the listener to remove

getSchema

public SimpleFeatureType getSchema()

Description copied from interface: FeatureSource

Retrieves the schema (feature type) that will apply to features retrieved from this FeatureSource.

For a homogeneous data source such as a shapefile or a database table, this schema be that of all features. For a heterogeneous data source, e.g. a GML document, the schema returned is the lowest common denominator across all features.

Specified by:

getSchema in interface FeatureSource<SimpleFeatureType,SimpleFeature>

Returns:

the schema that will apply to features retrieved from this FeatureSource

getBounds

public ReferencedEnvelope getBounds()
                             throws IOException

Description copied from interface: FeatureSource

Get the spatial bounds of the feature data. This is equivalent to calling getBounds(Query.ALL).

It is possible that this method will return null if the calculation of bounds is judged to be too costly by the implementing class. In this case, you might call getFeatures().getBounds() instead.

Specified by:

getBounds in interface FeatureSource<SimpleFeatureType,SimpleFeature>

Returns:

The bounding envelope of the feature data; or null if the bounds are unknown or too costly to calculate.

Throws:

IOException - on any errors calculating the bounds

getBounds

public ReferencedEnvelope getBounds(Query query)
                             throws IOException

Description copied from interface: FeatureSource

Get the spatial bounds of the features that would be returned by the given Query.

It is possible that this method will return null if the calculation of bounds is judged to be too costly by the implementing class. In this case, you might call getFeatures(query).getBounds() instead.

Specified by:

getBounds in interface FeatureSource<SimpleFeatureType,SimpleFeature>

Parameters:

query - the query to select features

Returns:

The bounding envelope of the feature data; or null if the bounds are unknown or too costly to calculate.

Throws:

IOException - on any errors calculating the bounds

getCount

public int getCount(Query query)
             throws IOException

Description copied from interface: FeatureSource

Gets the number of the features that would be returned by the given Query, taking into account any settings for max features and start index set on the Query.

It is possible that this method will return -1 if the calculation of number of features is judged to be too costly by the implementing class. In this case, you might call getFeatures(query).size() instead.

Example use:

 int count = featureSource.getCount();
 if( count == -1 ){
    count = featureSource.getFeatures( "typeName", count ).size();
 }

Specified by:

getCount in interface FeatureSource<SimpleFeatureType,SimpleFeature>

Parameters:

query - the query to select features

Returns:

the numer of features that would be returned by the Query; or -1 if this cannot be calculated.

Throws:

IOException - if there are errors getting the count

getSupportedHints

public Set<RenderingHints.Key> getSupportedHints()

Description copied from interface: FeatureSource

Returns the set of hints that this FeatureSource supports via Query requests.

Note: the existence of a specific hint does not guarantee that it will always be honored by the implementing class.

Specified by:

getSupportedHints in interface FeatureSource<SimpleFeatureType,SimpleFeature>

Returns:

a set of RenderingHints#Key objects; may be empty but never null

See Also:

• Hints.FEATURE_DETACHED
• Hints.JTS_GEOMETRY_FACTORY
• Hints.JTS_COORDINATE_SEQUENCE_FACTORY
• Hints.JTS_PRECISION_MODEL
• Hints.JTS_SRID
• Hints.GEOMETRY_DISTANCE
• Hints.FEATURE_2D

getFeatures

public SimpleFeatureCollection getFeatures()
                                    throws IOException

Description copied from interface: FeatureSource

Retrieves all features in the form of a FeatureCollection.

The following statements are equivalent:

     featureSource.getFeatures();
     featureSource.getFeatures(Filter.INCLUDE);
     featureSource.getFeatures(Query.ALL);
 

Specified by:

getFeatures in interface FeatureSource<SimpleFeatureType,SimpleFeature>

Specified by:

getFeatures in interface SimpleFeatureSource

Returns:

features retrieved by the Query

Throws:

IOException - if the underlying data source cannot be accessed.

getFeatures

public SimpleFeatureCollection getFeatures(Filter filter)
                                    throws IOException

Description copied from interface: FeatureSource

Retrieves features, in the form of a FeatureCollection, based on an OGC Filter.

Specified by:

getFeatures in interface FeatureSource<SimpleFeatureType,SimpleFeature>

Specified by:

getFeatures in interface SimpleFeatureSource

Parameters:

filter - the filter to select features; must not be null (use Filter.INCLUDE instead)

Returns:

features retrieved by the Filter

Throws:

IOException - if the underlying data source cannot be accessed.

See Also:

• Filter

getFeatures

public SimpleFeatureCollection getFeatures(Query query)
                                    throws IOException

Description copied from interface: FeatureSource

Retrieves features, in the form of a FeatureCollection, based on a Query.

Specified by:

getFeatures in interface FeatureSource<SimpleFeatureType,SimpleFeature>

Specified by:

getFeatures in interface SimpleFeatureSource

Parameters:

query - DataAccess query for requested information, such as typeName, maxFeatures and filter.

Returns:

features retrieved by the Query

Throws:

IOException - if the underlying data source cannot be accessed.

See Also:

• Query